Trees are big

I was outside talking to my neighbor when we both heard a cracking sound. 
Then a huge crack and followed by a thunderous crash.  One of their trees had fallen. It was really  weird to have it happen so we could witness it.  I have finally answered that age old question if no one is in the woods is there any noise.  The answer no it is silent.  There are only sound waves in the woods.  You would need receptor (ears) to hear the noise.